The sum of 1st and 9th term of an AP is 44. its 4th term is 18. What is its 6th term?
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Step-by-step explanation:
a1 + a9 = 44
Using Formula, an = a+(n-1)d
[a + (1-1)d] + [a+(9-1)d] = 44
(a + 0) + (a+8d) = 44
a + a + 8d = 44
2a + 8d = 44
a + 4d = 22 __________(1)
a4 = 18
[a+(4-1)d] = 18
a + 3d = 18____________(2)
Solving eq. 1 and 2
a + 4d = 22
a + 3d = 18
= d = 4
Putting value of d in eq. 1
a + 4d = 22
a + 4×4 = 22
a + 16 = 22
a = 22 - 16 = 6
Finding 6th term
an = a + (n - 1)d
a6 = 6 + (6-1) × 4
= 6 + 5 × 4
= 6 + 20
= 26
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